Casing centralizer



March 2 7, 1951 fa; D

R. c. BAKER 2,546,582

CASING CENTRALIZER Filed March 1, 1948 f2 j@ Y( f f2 i e gli? 2 j f2 l@fa 1/ me? Ms Av ,Av

INVENTOR., aewcgaet @QW a. 7%,

arme/VE# Patented Mar. 27, 1951 CASING CENTRALIZER Reuben C. Baker,Coalinga, Calif., `a.ssi,,frior to Baker Oil Tools, Inc., Vernon,Calif., Ya corpoporation of California Applieation'March 1, 1948, SerialN0. 12,263

The -presentinvention relates to centralizers,

wand more particularly to centralizers for centering casing, liners, andsimilar Vconduits in Well fbores.

It is preferred to pull, and ,not push, casing centralizers embodyingoutwardly bowed leaf springs through restrictions in'well bores as thecasing on which the centralizer isi-mounted is elevated or lowered. The'pulling action facilitates passage of the centralizer through therestric `tion without danger of damage to the parts. Especially inconnection with the cementing of a string of casing in a well bore, itis sometimes desirable lto rotate the casing to insure the uni- .formdistribution vof cement around its exterior. Such rotation lshould beimparted tothe casing without ,any need for rotating the centralizer, inview of the dragging of the outwardly bowed centralizer springs aroundthe wall of the formation,

with consequent damage Or destruction to its parts.

It is, accordingly, an object of the present invention to provide asimple, sturdy, and comparatively inexpensive casing centralizer, whichcan be pulled through the well bore upon movement of the casing stringtherein in either longitudinal direction, and which .permits rotation ofthe casing string without corresponding rotation .of :the centralizeritself.

.fffIhe invention has other objects that vwill .become apparent from aconsideration of the embodiment shown in the drawings accompanying andforming part of the present specication. This form will now be describedin detail; but it is to be understood that such detailed descriptionshould be taken in a limiting sense, since the scope of the invention isbest dened by the appended claims.

Referring to the drawings:

Figure 1 is a side elevation of a casing centralizer mounted upon acasing section disposed in a well bore;

Fig. 2 is an enlarged cross section, taken along the line 2-2 on Fig. 1;and

Fig. 3 is a partial, isometric, exploded view of the centralizer.

The casing centralizer A is mounted upon a. section of casing B formingpart of a casing ls tring,`in order to center the latter in a well boreC in which it is disposed. The centralizer includes longitudinallyspaced upper and lower generally cylindrical collars lil, II, to which aplurality of circularly spaced, outwardly bowed springs I2 are secured.These collars are slidably mounted upon the casing section B, in orderto 3 Claims. (Cl. 16d-4) permit relative longitudinal and rotarymovement to take place therebetween.

It is to be noted that each collar has a plurality of circularly spaced,longitudinally extending slots I3 corresponding in number and angularspacing tothe leaf springs I2. The `inner ends I4 of these slots aredisposed inwardly of the inner end l5 oi each collar, and their .outerends l5 are disposed inwardly of the outer end Il ci the collar.Accordingly, the inner ends I5 of the collars are circumferentiallycontinuous and provide a smooth surface upon kwhich other elements arenot prone to catch or snag.

The ends E8 of the leaf springs VI2 are disposed over the inner ends vI5of the collars, tting within the slots i3, `with the terminal portionsiS of the springs abutting the collar` material at the outer ends I6 ofthe slots. Such terminal portions are firmly secured vto thecollar atthe outer ends or the slots by weldingma'terial 29. A satisfactory weldcan be performed in several different manners without substantially`aiecting `the properties of the leaf springs I2. It has been found thatan atomic hydrogen arc weld integratos the ends L9 of the springs to thecollars I, IVI without failure of the welds 2!! or of the centralizerparts themselves upon collapsing'of the springs inwardly to their.fullest vextent against the casing section B.

For the purpose oi moving the centralizer A through` the well bore withthe casing string A, a stop ring 2l is attached to 'the casing sectionbetween the upper and lower collars I, I I. This ring may be splitinitially to facilitate its mounting on the casing section B between thecollar members. Thereafter, it is secured to the casing section bydepositing welding material 22 in holes 23 provided in the ring. Inaddition, if deemed necessary, the adjacent ring ends deiining the split24 may also be welded to one another and to the casing B. l

Because of the location oi the stop ring 2l between the upper and lowercollars I0, II, the casing centralizer will be pulled through the wellbore regardless of the direction of longitudinal movement of the casingB therein. Downward movement of the casing engages the stop ring 2I withthe inner circumferentially continuous portion I5 of the lower collar II, exerting a pulling action on the outwardly bowed springs I 2.Similarly, upward movement of the casing string engages the stop ring 2|with the circumferentially continuous inner portion I5 of the uppercollar IU, and causes an upward pulling action to be exerted on theoutwardly bowed spring I2. Full bearing engagement of the stop ring 2Iwith either collar is assured because of the circumferential continuityof the inner ends I5 of the collars and the fact that the bowed springsI2 are disposed over the exterior of such circumferentially continuousportions. As a result, the springs do not interfere with engagement ofthe ring with the collars. Of course, to avoid such interference, theexternal diameter of the stop ring 2| is preferably no greater than theexternal diameter of the collars themselves.

In addition to insuring the pulling of the centralizer through the wellbore, as distinguished from its being pushed through the well bore, thecasing string B may be rotated freely within the upper and lower collarsI0, II of the centralizer.

This is evident, since there is no' connection whatsoever between thecasing and the collars. The stop ring 2| will either be disposed out ofengagement with both collars I0, II, so as not to interfere with thefree rotation of the casing within the collars, or they may actually beengaged with either collar and will still allow the casing to be freelyrotated within the collar, since the stop ring merely rides along thecircumferentially continuous inner end I5 of the collar.

The inability of the casing string B to rotate the casing centralizer Ainsures the ability of the casing string to rotate freely, and alsoinsures against the necessity for dragging the centralizer springs I2around the walls of the formation, which might produce their breakage.

It is apparent that the centralizer is relatively simple and compact, inview of its comparatively few parts. Its overall maximum diameter, whenthe springs I2 are in fully collapsed condition against the casing, isthe outside diameter of a collar I0 or II, plus twice the thickness of acentralizer spring. This small overall diameter permits the centralizerto be moved through other casing sections and through Well bores whoseinternal diameters are only slightly greater than the external diameterof the casing on which'the centralizer is mounted. In addition, thecollapsed external diameter of the centralizer is very little, if any,greater than the external diameter lof the usual casing collars whichcouple the casincluding a pair of members, said members havingcircumferentially continuous inner ends facing each other and alsohaving circularly spaced slots longitudinally spaced away from saidinner ends; outwardly bowed springs extending between said members, theends of said springs being disposed over the inner ends of said membersand extending into said slots, at which points they are secured to saidmembers; and stop means disposed between and engageable with said innerends of said members.

2. A centering device; including a pair of spaced, generally cylindricalmembers, said members having circumferentially continuous inner endsfacing each other and also having circularly spaced slots longitudinallyspaced away from said inner ends; outwardly bowed springs extendingbetween said members, the ends of said springs being disposed over theinner ends of said members and extending into said slots, said springends being welded to said members at the outer ends of said slots; and astopt ring disposed between and engageable with said inner ends of saidmembers.

3. In combination with a casing; a centering device including a pair ofspaced, generally cylindrical members slidable on said casing, saidmembers having circumferentially continuous inner ends facing each otherand also having circularly spaced slots longitudinally spaced away fromsaid inner ends; outwardly bowed springs extending between said members;the ends of said springs being disposed over the inner ends of saidmembers and extending into said slots, said spring ends being welded tosaid members at the outer ends of said slots; and a stop ring secured tosaid casing between said members for selective engagement with thecircumferentially continuous inner ends of said members.

REUBEN C. BAKER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNTED STATES PATENTS Number Name Date 1,775,376 Steps et al. Sept. 9,1930 2,089,553 Hartman et al. Aug. 10, 1937 2,312,600 Steps Mar. 2, 1943

